Bioleaching of copper from low grade scrap TV circuit boards using mesophilic bacteria

Abstract

In this study, the extraction of copper from manufacturing scrap TV circuit boards (STVB) by bacteria-assisted leaching was studied using a mixed culture of mesophilic bacteria. Initial availability of soluble iron appeared to be of prime importance for the extraction of copper from STVB, which contains 43g/ton Fe. In this respect, the addition of 1–8g/L Fe(II) significantly improved (by up to 54%) the extraction of copper from STVB at the expense of the increased acid consumption. A new approach for the bioleaching process was adopted, which is based on the addition of pyrite (5–50g/L pyrite concentrate (PyC)) as a source of iron and sulphur. Copper extraction was observed to enhance from 24% to 84% in the presence of 50g/L PyC with a significant decrease (62%) in the consumption of acid. An increase in the size of inoculum from 10% to 50% v/v was also observed to improve the bioleaching rate of copper. The findings in the current study highlight the practical importance of the availability of iron (and hence, iron content of wastes) for the successful development of a bioleaching process for e-waste and the potential for utilisation of pyrite as a suitable source of iron and sulphur in bioleaching of e-waste.